中华绒螯蟹蜕皮过程中体壁结构和主要成分的变化

采用组织化学和原子吸收分析等方法, 研究了中华绒螯蟹蜕皮过程中体壁结构和主要成分的变化。结果显示: 中华绒螯蟹体壁分为上表皮、外表皮、内表皮和膜层, 糖类物质各层均有分布, 胶原纤维分布在除上表皮外的其他各层。在蜕皮前, 糖类、胶原纤维都被重吸收, 体壁上表皮和外表皮在蜕皮前形成, 内表皮和膜层在蜕皮后形成。体壁粗蛋白含量在蜕皮前期(D1-D3-4期)降低(P0.05), 蜕皮后A-B期含量极高(P0.05)。几丁质含量在蜕皮过程中变化不显著(P0.05), 只是在蜕皮前稍有上升。Ca2+和Mg2+含量在蜕皮前D1期显著低于蜕皮间期和蜕皮前其他时期(P0.05), 而蜕皮后A-B期降到最低(P0.05), 蜕下的甲壳中则含有较多的Ca2+和Mg2+ (P0.05)。Cu2+和Zn2+含量除蜕皮后A-B期升高外(P0.05), 其余时期变化不明显(P0.05)。这些研究结果表明, 中华绒螯蟹体壁结构和成分变化与蜕皮周期密切相关。       

中华绒螯蟹不同部位游离氨基酸的测定与分析

本文对中华绒螯蟹不同部位的游离氨基酸含量和组成进行测定,结果显示：中华绒螯蟹步足肌肉、腹部肌肉和蟹黄这三个部位的游离氨基酸总量、呈味氨基酸总量、必需氨基酸总量和限制性氨基酸总量存在显著差异性。此外,阳澄湖蟹和池塘养殖蟹的各部位游离氨基酸含量和组成也存在很大差异性。     

中华绒螯蟹（Eriocheir sinensis）体内维生素C含量与死亡和产卵的关系

本文报道了中华绒螯蟹越冬后肝胰脏、肌肉和生殖腺维生素Ｃ的含量及变化。肝胰脏为中华绒螯蟹储存维生素Ｃ的器官;越冬后的雌性中华绒螯蟹,其肌肉和生殖腺的维生素Ｃ高于雄性;正常活动雌性或雄性,其肝胰脏、肌肉和生殖腺的维生素Ｃ含量均高于死亡的个体的维生素Ｃ含量;产卵且抱卵孵化的雌体,其肝脏维生素Ｃ的含量高于那些不产卵的雌体,维生素Ｃ含量的降低是越冬时或越冬后中华绒螯蟹死亡的主要原因之一。     

中华绒螯蟹（Eriocheir sinensis）体内维生素C含量与死亡和产…

本文报道了中华绒螯蟹越冬后肝胰脏、肌肉和生殖腺维生素Ｃ的含量及变化。肝胰脏为中华绒螯蟹储存维生素Ｃ的器官;越冬后的雌性中华绒螯蟹,其肌肉和生殖腺的维生素Ｃ高于雄性;正常活动雌性或雄性,其肝胰脏、肌肉和生殖腺的维生素Ｃ含量均高于死亡的个体的维生素Ｃ含量;产卵且抱卵孵化的雌体,其肝脏维生素Ｃ的含量高于那些不产卵的雌体。维生素Ｃ含量的降低是越冬时或越冬后中华绒螯蟹死亡的主要原因之一。     

河蟹的生物学特性及其养殖技术

一、河蟹的生物学特性 1、外部形态河蟹,学名中华绒螯蟹,又称毛蟹、螃蟹、大闸蟹,是一种全身被一层坚韧甲壳的高等甲壳类动物。在河蟹的头胸部两侧,左右对称着生五对胸足。第一对特别发达,称螯足。其余四对胸足结构相同,均称步足。由于河蟹经常依靠强壮的步足在水底爬行,与其相关的腹部及腹部附肢就随之退化,成一薄片,卷贴于头胸部之下,称为蟹脐。在幼蟹阶段,雌雄个体的腹部均为狭长形。但随着生长,雌蟹腹部渐呈圆形,雄蟹渐呈狭长的三角形。前者称团脐,后者称尖脐,这     

中华绒螯蟹对Pb和Cd的富集与释放特性

应用生物富集双箱动力学模型模拟了中华绒螯蟹(Eriocheir sinensis)分别在Pb浓度为0.25、0.50、0.75mg/L,Cd浓度为0.025、0.050、0.075mg/L的单一水环境中暴露时,蟹鳃、肝胰腺、肌肉和血淋巴对Pb和Cd的生物富集与释放实验,并通过非线性拟合得到中华绒螯蟹对Pb和Cd的富集速率常数k1、排出速率常数k2、生物富集系数BCF、生物半衰期B1/2、富集平衡时生物体内Pb和Cd含量CAmax等动力学参数。结果表明:(1)中华绒螯蟹对Pb和Cd具有明显的富集,蟹鳃、肝胰腺和肌肉中Pb和Cd的含量与富集时间和水环境中Pb和Cd暴露浓度表现出了很好的正相关,血淋巴在富集阶段没有明显的规律。理论平衡状态下鳃、肝胰腺和肌肉中Pb和Cd含量CAmax随着暴露浓度的增大而增大,且成正相关。(2)Pb和Cd在中华绒螯蟹组织器官中的富集具有选择性,开始实验前,Pb在中华绒螯蟹体内的的分布规律为:肝胰腺>鳃>肌肉>血淋巴;Cd的分布规律为:鳃>肝胰腺>血淋巴>肌肉。在实验浓度的Pb和Cd水环境中暴露16d后,Pb的分布规律为:鳃>肝胰腺>肌肉>血淋巴;Cd的分布规律为:肝胰腺>鳃>肌肉>血淋巴。(3)中华绒螯蟹对Pb和Cd的生物富集和释放都较缓慢。经过16d的生物富集,各组织器官中Pb和Cd的含量均未达到稳态平衡。Pb和Cd在组织器官中的生物富集系数(BCF)范围分别为5-51和6-3148,中华绒螯蟹对Cd的富集能力明显高于Pb(P1/2)范围分别为4-9d和8-57d,中华绒螯蟹对Cd的排出能力明显低于Pb。       

饥饿对中华绒螯蟹(Eriocheir sinensis)幼体发育的影响

对刚孵化的中华绒螯蟹第一期的蚤状幼体经不同时间的饥饿后再投喂,发现饥饿可以明显降低幼体的存活率和延长幼体的发育期。实验表明:对中华绒螯蟹第一期的蚤状幼体的饥饿时间(t)和发育期长(D)呈线性关系(D=4.6303+1.3226t r=0.970p<0.01)。对于中华绒螯蟹第一期的蚤状幼体,当起始饥饿时间超过了4d,再予以投饵,幼体均不能恢复正常的发育和蜕皮功能,得出中华绒螯蟹的不可恢复点(the point of no-return,PNR)大约为4d。通常以产生50%的幼体死亡的饥饿期即PNR₅₀,来表明幼体对饥饿的抵抗能力,实验得出中华绒螯蟹第一期的蚤状幼体的PNR₅₀大约为48h。     

CuSO4对中华绒螯蟹蜕皮、生长和存活的影响

通过向水中添加不同浓度的铜(Cu2 ),观察其对中华绒螯蟹(Eriocheir sinensis)Ⅰ期幼蟹(0.020±0.01g)和12月龄扣蟹(3.34±0.26 g)的毒性影响。Cu2 对Ⅰ期幼蟹24,48,72和96h的半致死浓度(LC50)分别为0.70,0.43,0.33和0.22 mg/L,而对12月龄扣蟹相应的LC50分别是18.20,10.23,9.12和8.51mg/L。中华绒螯蟹Ⅰ期幼蟹在0.00,0.01,0.02,0.03,0.05和0.08mg/L Cu2 的水环境中的蜕皮率、增重率和存活率的比较研究结果表明,虽然各浓度组存活率均高于50%,但其随着Cu2 浓度的增高而降低。增重率和蜕皮率的变化趋势与存活率相似。此外,研究了中华绒螯蟹12月龄扣蟹在0.00,0.01,0.05,0.10,0.50,1.00和2.50 mg/L Cu2 的水环境中蜕皮率、增重率和存活率的变化。结果显示,各组存活率均高于50%,除0.01mg/L处理组的存活率略高于对照组外,总的变化趋势是随着Cu2 浓度的增高而降低。增重率和蜕皮率随着Cu2 浓度的增高,总的变化趋势亦逐渐降低。相关性分析表明,中华绒螯蟹Ⅰ期幼蟹和12月龄扣蟹的生长、蜕皮和存活与水中添加Cu2 的浓度增加有极显著的负相关(P<0.01)。     

中华绒螯蟹肠道内间质样细胞的显微和超微结构观察

目的探究中华绒螯蟹(Eriocher sinens is)肠道中是否存在间质样细胞。方法通过对中华绒螯蟹中肠和后肠进行全层铺片和肠cajal间质细胞(interstitial cells of cajal,ICC)特殊染色法碘化锌-锇酸(zinc iodide-osmium,ZIO)染色,并结合后肠透射电镜观察中华绒螯蟹后肠ICC样细胞分布及形态。结果光镜检查结果显示:中华绒螯蟹间质样细胞常分布在中肠和后肠的黏膜下层。这些细胞形态相似,多为圆形或卵圆形,胞体直径约为10μm左右,呈灰黑色,常成群呈块状或片状分布,在后肠中的分布更为密集。电镜检测结果显示:这些细胞分布于黏膜下层、肌层与肌层之间和肌肉束边缘。后肠中间质样细胞多为梭形及纺锤形,也有不规则型,常有两个或两个以上突起,与邻近的细胞连接方式多为缝隙连接。此外,本研究还在后肠肠道固有膜层、肌层间和黏膜下层发现了大量颗粒细胞的分布。结论本研究通过传统的特异性ZIO染色和超微形态的观察初步发现中华绒螯蟹肠道内有ICC样细胞的分布。     

中华绒螯蟹水通道蛋白11基因克隆及表达分析

为研究水通道蛋白11基因(AQP11)在中华绒螯蟹(Eriocheir sinensis)生长蜕壳过程中的功能作用,采用RACE技术克隆获得中华绒螯蟹水通道蛋白11基因cDNA全长序列.该序列总长为1 746bp,5'端和3'端非编码区分别为463 bp和476 bp,开放阅读框为807 bp,推测编码268个氨基酸,预测分子量29.46 kDa,理论等电点为5.38.生物学信息分析表明,AQP11含有4个跨膜区(第62～84,第159～181,第194～216,第231～250)和2个NPV单元,属于稳定蛋白;同源性和进化树分析表明,中华绒螯蟹AQP11氨基酸序列与凡纳滨对虾(Litopenaeus vannamei)的同源性最高(82.0％),与凡纳滨对虾的聚为一支,与甲壳动物的亲缘关系最近.实时荧光定量PCR(RT-qPCR)的检测显示,AQP11基因在中华绒螯蟹各组织中均有表达,其中在肠道中表达量最高,其次是脑、肌肉和胸神经节,在肝胰腺、鳃和血中表达量最低.研究发现,AQP11基因在中华绒螯蟹肠道中的表达呈现,在蜕壳间期(C期)和蜕壳前期(D期)过程中表达量均较低,在蜕壳期(E期)表达量开始上升,蜕壳后期(AB期)表达量不变.AQP11基因在肌肉中的表达呈现,蜕壳间期(C期)表达量低,蜕壳前期(D期)表达量开始上升,蜕壳期(E期)达到峰值,随后到蜕壳后期(AB期)下降.研究结果表明,中华绒螯蟹AQP11基因在其蜕壳过程中发挥着重要的作用.     

Proteasomal activities in the claw muscle tissue of European lobster, Homarus gammarus, during larval development

Decapod crustaceans grow discontinuously and gain size through complex molt processes. The molt comprises the loss of the old cuticle and, moreover, substantial reduction and re-organization of muscles and connective tissues. In adult lobsters, the muscle tissue of the massive claws undergoes significant atrophy of 40-75% before ecdysis. The degradation of this tissue is facilitated by calcium-dependent proteases and by the proteasome, an intra-cellular proteolytic multi-enzyme complex. In contrast to the adults, the involvement of the proteasome during the larval development is yet not validated. Therefore, we developed micro-methods to measure the 20S and the 26S proteasomal activities within mg- and sub-mg-quantities of the larval claw tissue of the European lobster, Homarus gammarus. Within the three larval stages (Z1-3) we distinguished between sub-stages of freshly molted/hatched (post-molt), inter-molt, and ready to molt (pre-molt) larvae. Juveniles were analyzed in the post-molt and in the inter-molt stage. The trypsin-like, the chymotrypsin-like, and the peptidyl-glutamyl peptide hydrolase activity (PGPH) of the 20S proteasome increased distinctly from freshly hatched larvae to pre-molt Z1. During the Z2 stage, the activities were highest in the post-molt animals, decreased in the inter-molt animals and increased again in the pre-molt animals. A similar but less distinct trend was evident in the Z3 stages. In the juveniles, the proteasomal activities decreased toward the lowest values. A similar pattern was present for the chymotrypsin-like activity of the 26S proteasome. The results show that the proteasome plays a significant role during the larval development of lobsters. This is not only reflected by the elevated activities, but also by the continuous change of the trypsin/chymotrypsin-ratio which may indicate a shift in the subunit composition of the proteasome and, thus, a biochemical adjustment to better cope with elevated protein turnover rates during larval development.     

Male Mating Tactics in the Shrimp Palaemonetes pugio (Decapoda, Caridea): Precopulatory Mate Guarding vs. Pure Searching

The guarding of females approaching a limited period of sexual receptivity is a common mating tactic of males. In many decapod crustaceans, such as the shrimp Palaemonetes pugio , females can only copulate during a short period after a reproductive molt. It has been predicted that mate guarding by males (pre-copula) evolves in such species if sex ratios are not highly female-biased and if males can detect the molt stage of the female. The mating tactics of males were investigated in P. pugio . Time-lapse video observations were made on interactions among two males, a pre-molt female, and an inter-molt female (20 replicates). There was no evidence that males recognized a pre-molt female until 24 h before its molt. Significant numbers of male contacts with pre-molt females occurred 1 h before and after the female molt. Copulation took place within 1–3 min of the molt. No behavior commonly associated with mate guarding in decapods was observed – no clasping, agonistic behavior, or close association. It is concluded that the male's mating tactic is pure searching, wherein males haphazardly contact many females in order to find a receptive one. The high encounter rate in nature of these very mobile, aggregated shrimps is proposed as the factor responsible for the evolution of pure searching. It is hypothesized that pure searching is the male tactic of the many species of decapod shrimps with small males, sexually monomorphic cheliped weapons, and aggregated populations.     

The syncytial nature and phagocytic activity of the branchial podocytes in the grass shrimp, Palaemonetes pugio

The morphology of the branchial podocytes in the grass shrimp, Palaemonetes pugio, was investigated in relation to the molt cycle. The podocytes are located in the efferent hemolymph channels in the gill axis, and possess a specialized plasmalemma consisting of interdigitating pedicel processes which are bridged by thin diaphragms. The topography of the plasmalemmal surface suggests that these cells, like similar cells in other arthropods, function in the ultrafiltration of micro- and macromolecular substances from the hemolymph. Additionally, the branchial podocytes exhibit phagocytic activity. This activity, though evident during the pre-molt period, is most prominent during the early post-molt period. Among the cell types subjected to phagocytosis by podocytes are the secretory cells of the tricellular and rosette-type dermal glands and the epithelial cells of the gill axis. During the late pre-molt and early post-molt periods, the podocytes often appear as syncytia, containing as many as four nuclei. The exact interrelationships between phagocytosis and syncytial formation remain to be ascertained. These aspects and the possible ambulatory abilities of the branchial podocytes are discussed.     

Adenylate energy charge, arginine phosphate and ATPase activity in juvenile Homarus americanus during the molt cycle

Neither gill nor hepatopancreas exhibited significant differences in Na+, K+-ATPase activity with molt stage. Hepatopancreatic residual ATPase activity was significantly higher (F = 6.273) in post-molt animals; while gill residual ATPase activity exhibited no significant differences. Muscle AEC did not change with molt stage, but levels of ATP (F = 8.050) and ADP (F = 4.130) were significantly higher in premolt (D3 pleopod stage 5.0-5.5) animals; while levels of arginine phosphate (F = 6.981) were significantly higher in post-molt animals. Arginine phosphate/ATP and ATP/ADP ratios were highest in post-molt animals, but were not statistically significant. Although not significant, changes in Na+, K+-ATPase activity and AEC did suggest alterations in: enzyme activity that correlate with known osmotic compensations occurring during the water uptake and hardening/mineralization processes; and energy metabolism which occur during the molt cycle, respectively.     

Neural activity pattern is not necessary for the development of adult ultrastructure in katydid (Neoconocephalus robustus) singing muscles

Summary The singing muscles of the katydid Neoconocephalus robustus develop adult ultrastructure late in the last nymphal instar and during the first few days of adult life. The ultrastructural changes during early adulthood were not affected by unilateral axotomy shortly after the adult molt. Both denervated and innervated muscles developed adult proportions of mitochondria, myofibril, and sarcoplasmic reticulum and transverse tubules.     

Identification of a transforming growth factor-β type I receptor transcript in Eriocheir sinensis and its molting-related expression in muscle tissues

The transforming growth factor-β (TGF-β) signaling pathway is conserved across animals, and knowledge of its roles during the molt cycle in crustaceans is presently very limited. This study investigates the roles of the TGF-β receptor in molting-related muscle growth in Eriocheir sinensis. Using the RT-PCR and RACE techniques, we obtained a 1722 bp cDNA sequence encoding a transforming growth factor-β type I receptor in Eriocheir sinensis, designated EsTGFBRI, which contains a 124 bp 5′-untranslated region, a 20 bp partial 3′-untranslated region and a 1578 bp open reading frame encoding 525 amino acids. The deduced EsTGFBRI contains an N-terminal 24 amino acid signal peptide, an activin type I and II receptor domain, a transmembrane helix region, a glycine-serine-rich motif, and a conserved serine/threonine kinase catalytic domain including an activation loop. The qRT-PCR results showed that EsTGFBRI gene was highly expressed in the intermolt testis and ovary in mature crabs. In juvenile crabs, the mRNA levels of EsTGFBRI in claw and abdominal muscles in the later premolt D_3–4 stage were significantly higher than those in the intermolt C and postmolt A–B stages. There was no significant change in EsTGFBRI mRNA levels in walking leg muscles during the molt cycle. The results suggest that EsTGFBRI is probably play roles in molting-related muscle growth in E. sinensis. This study provides a necessary basis for elucidating the functions of TGF-β-like signaling mediated by TGFBRI in molting-related muscle growth in crustaceans.

     

Changes in plasma thyroid hormones, luteinizing hormone (LH), estradiol, progesterone and corticosterone of laying hens during a forced molt

1. Circulating concentrations of iodothyronines, luteinizing hormone(LH), estradiol(E2), progesterone and corticosterone were measured in hens before, during, and after a forced molt induced by fasting. 2. Corticosterone increased at the onset of molt, peaked at the maximal molt and returned to pre- and post-molt levels. LH, E2 and progesterone declined during the molt, and the decline was coincident with the cessation of egg production. 3. Thyroxine(T4), triiodothyronine (T3) and reverse triiodothyronine(rT3) increased during the molt. The increases of T4 and T3 were not abolished even if the forced molt was conducted in mild weather.